kernel/linux.git/fs/proc/kcore.c, branch v6.19.11

crash: Use note name macros

2025-02-11T00:56:58+00:00

Use note name macros to match with the userspace's expectation. Signed-off-by: Akihiko Odaki Acked-by: Baoquan He Reviewed-by: Dave Martin Link: https://lore.kernel.org/r/20250115-elf-v5-4-0f9e55bbb2fc@daynix.com Signed-off-by: Kees Cook

proc/kcore: use percpu_rw_semaphore for kclist_lock

2024-12-02T10:21:07+00:00

The list of memory ranges for /proc/kcore is protected by a rw_semaphore. We lock it for reading on every read from /proc/kcore. This is very heavy, especially since it is rarely locked for writing. Since we want to strongly favor read lock performance, convert it to a percpu_rw_semaphore. I also experimented with percpu_ref and SRCU, but this change was the simplest and the fastest. In my benchmark, this reduces the time per read by yet another 20 nanoseconds on top of the previous two changes, from 195 nanoseconds per read to 175. Link: https://github.com/osandov/drgn/issues/106 Signed-off-by: Omar Sandoval Link: https://lore.kernel.org/r/83a3b235b4bcc3b8aef7c533e0657f4d7d5d35ae.1731115587.git.osandov@fb.com Signed-off-by: Christian Brauner

proc/kcore: don't walk list on every read

2024-12-02T10:21:07+00:00

We maintain a list of memory ranges for /proc/kcore, which usually has 10-20 entries. Currently, every single read from /proc/kcore walks the entire list in order to count the number of entries and compute some offsets. These values only change when the list of memory ranges changes, which is very rare (only when memory is hot(un)plugged). We can cache the values when the list is populated to avoid these redundant walks. In my benchmark, this reduces the time per read by another 20 nanoseconds on top of the previous change, from 215 nanoseconds per read to 195. Link: https://github.com/osandov/drgn/issues/106 Signed-off-by: Omar Sandoval Link: https://lore.kernel.org/r/8d945558b9c9efe74103a34b7780f1cd90d9ce7f.1731115587.git.osandov@fb.com Signed-off-by: Christian Brauner

proc/kcore: mark proc entry as permanent

2024-12-02T10:21:03+00:00

drgn reads from /proc/kcore to debug the running kernel. For many drgn scripts, /proc/kcore is actually a bottleneck. use_pde() and unuse_pde() in prog_reg_read() show up hot in profiles. Since the entry for /proc/kcore can never be removed, this is useless overhead that can be trivially avoided by marking the entry as permanent. In my benchmark, this reduces the time per read by about 20 nanoseconds, from 235 nanoseconds per read to 215. Link: https://github.com/osandov/drgn/issues/106 Signed-off-by: Omar Sandoval Link: https://lore.kernel.org/r/60873e6afcfda3f08d0456f19e4733612afcf134.1731115587.git.osandov@fb.com Signed-off-by: Christian Brauner

Merge tag 'vfs-6.13-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2024-11-27T16:11:46+00:00

Pull vfs fixes from Christian Brauner: - Fix a few iomap bugs - Fix a wrong argument in backing file callback - Fix security mount option retrieval in statmount() - Cleanup how statmount() handles unescaped options - Add a missing inode_owner_or_capable() check for setting write hints - Clear the return value in read_kcore_iter() after a successful iov_iter_zero() - Fix a mount_setattr() selftest - Fix function signature in mount api documentation - Remove duplicate include header in the fscache code * tag 'vfs-6.13-rc1.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: fs/backing_file: fix wrong argument in callback fs_parser: update mount_api doc to match function signature fs: require inode_owner_or_capable for F_SET_RW_HINT fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero statmount: fix security option retrieval statmount: clean up unescaped option handling fscache: Remove duplicate included header iomap: elide flush from partial eof zero range iomap: lift zeroed mapping handling into iomap_zero_range() iomap: reset per-iter state on non-error iter advances iomap: warn on zero range of a post-eof folio selftests/mount_setattr: Fix failures on 64K PAGE_SIZE kernels

fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

2024-11-22T11:08:43+00:00

If iov_iter_zero succeeds after failed copy_from_kernel_nofault, we need to reset the ret value to zero otherwise it will be returned as final return value of read_kcore_iter. This fixes objdump -d dump over /proc/kcore for me. Cc: stable@vger.kernel.org Cc: Alexander Gordeev Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses") Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20241121231118.3212000-1-jolsa@kernel.org Acked-by: Alexander Gordeev Signed-off-by: Christian Brauner

fs/proc/kcore.c: fix coccinelle reported ERROR instances

2024-11-06T21:36:37+00:00

Coccinelle complains about the nested reuse of the pointer `iter' with different pointer type: ./fs/proc/kcore.c:515:26-30: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:534:23-27: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:550:40-44: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:568:27-31: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:581:28-32: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:599:27-31: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:607:38-42: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:614:26-30: ERROR: invalid reference to the index variable of the iterator on line 499 Replacing `struct kcore_list *iter' with `struct kcore_list *tmp' doesn't change the scope and the functionality is the same and coccinelle seems happy. NOTE: There was an issue with using `struct kcore_list *pos' as the nested iterator. The build did not work! [akpm@linux-foundation.org: s/tmp/pos/] Link: https://lkml.kernel.org/r/20241029054651.86356-2-mtodorovac69@gmail.com Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] Link: https://lkml.kernel.org/r/20220331223700.902556-1-jakobkoschel@gmail.com Fixes: 04d168c6d42d ("fs/proc/kcore.c: remove check of list iterator against head past the loop body") Signed-off-by: Jakob Koschel Signed-off-by: Mirsad Todorovac Cc: Mike Rapoport Cc: David Hildenbrand Cc: Oscar Salvador Cc: "Brian Johannesmeyer" Cc: Cristiano Giuffrida Cc: "Bos, H.J." Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Yang Li Cc: Baoquan He Cc: Hari Bathini Cc: Yan Zhen Cc: Alexander Gordeev Signed-off-by: Andrew Morton

fs/proc/kcore.c: allow translation of physical memory addresses

2024-10-09T19:47:19+00:00

When /proc/kcore is read an attempt to read the first two pages results in HW-specific page swap on s390 and another (so called prefix) pages are accessed instead. That leads to a wrong read. Allow architecture-specific translation of memory addresses using kc_xlate_dev_mem_ptr() and kc_unxlate_dev_mem_ptr() callbacks similarily to /dev/mem xlate_dev_mem_ptr() and unxlate_dev_mem_ptr() callbacks. That way an architecture can deal with specific physical memory ranges. Re-use the existing /dev/mem callback implementation on s390, which handles the described prefix pages swapping correctly. For other architectures the default callback is basically NOP. It is expected the condition (vaddr == __va(__pa(vaddr))) always holds true for KCORE_RAM memory type. Link: https://lkml.kernel.org/r/20240930122119.1651546-1-agordeev@linux.ibm.com Signed-off-by: Alexander Gordeev Suggested-by: Heiko Carstens Cc: Vasily Gorbik Cc: Signed-off-by: Andrew Morton

proc: Fix typo in the comment

2024-09-09T07:51:16+00:00

The deference here confuses me. Maybe here want to say that because show_fd_locks() does not dereference the files pointer, using the stale value of the files pointer is safe. Correctly spelled comments make it easier for the reader to understand the code. replace 'deferences' with 'dereferences' in the comment & replace 'inialized' with 'initialized' in the comment. Signed-off-by: Yan Zhen Link: https://lore.kernel.org/r/20240909063353.2246419-1-yanzhen@vivo.com Signed-off-by: Christian Brauner

crash: split vmcoreinfo exporting code out from crash_core.c

2024-02-24T01:48:22+00:00

Now move the relevant codes into separate files: kernel/crash_reserve.c, include/linux/crash_reserve.h. And add config item CRASH_RESERVE to control its enabling. And also update the old ifdeffery of CONFIG_CRASH_CORE, including of and config item dependency on CRASH_CORE accordingly. And also do renaming as follows: - arch/xxx/kernel/{crash_core.c => vmcore_info.c} because they are only related to vmcoreinfo exporting on x86, arm64, riscv. And also Remove config item CRASH_CORE, and rely on CONFIG_KEXEC_CORE to decide if build in crash_core.c. [yang.lee@linux.alibaba.com: remove duplicated include in vmcore_info.c] Link: https://lkml.kernel.org/r/20240126005744.16561-1-yang.lee@linux.alibaba.com Link: https://lkml.kernel.org/r/20240124051254.67105-3-bhe@redhat.com Signed-off-by: Baoquan He Signed-off-by: Yang Li Acked-by: Hari Bathini Cc: Al Viro Cc: Eric W. Biederman Cc: Pingfan Liu Cc: Klara Modin Cc: Michael Kelley Cc: Nathan Chancellor Cc: Stephen Rothwell Cc: Yang Li Signed-off-by: Andrew Morton